This paper is based on my talk presented in a conference entitled “The 50th Anniversary Workshop of the Disk Instability Model in Compact Binary stars”.
I review the history of the disk instability model (DIM) as the outburst mechanism of dwarf novae from my personal perspective. I first discuss my 1974 proposal of a working hypothesis for disk instability in dwarf novae— now known as the Disk Instability Model (DIM)—and the intense debate in late 1970s with the competing mass-transfer burst (MTB) model. The discovery in the early 1980s of the thermal-viscous instability as the physical mechanism underlying the disk instability resolved this longstanding controversy. I then describe the Thermal-Tidal Instability (TTI) model for the superoutburst and superhump phenomena of the SU UMa -type dwarf novae and finally present a unification model for the cataclysmic variable stars based on the TTI framework.